Radial-piston pump with improved cooling and lubrication



July 7, 1970 A. BLEUEL 3,519,370

RADIAL-PISTON PUMP WITH IMPROVED COOLING AND LUBRICATION Filed March 15,1968 2 Sheets-Sheet 1 FlG.l

ALOYS BLEUEL INVENTOR.

BY 5km T ATTORNEY July 7, 1970 A. BLEUEL 3,519,370

RADIAL-PISTON PUMP WITH IMPROVED COOLING AND LUBRICATION Filed March 13,1968 2 Sheets-Sheet 2 ALOYS BLEUEL INVENTOR.

ATTORNEY United States Patent T 3,52 Int. Cl. F04b 23/04, 1/04, 39/02US. Cl. 103-5 4 Claims ABSTRACT OF THE DISCLOSURE In a radial pistonpump the hydraulic fluid is shunted on its path between the reservoirand the piston cylinders to flow past moving parts at the eccentric ofthe pump so as to cool and lubricate the latter, the shunt pathincluding an axial bore formed in the eccentric shaft and openingbeneath the bearing ring surrounding the eccentric.

The invention relates to a radial-piston pump supplying hydraulicpressure by means of an eccentric shaft which rotates in a cylinderhousing in which the pumping pistons are radially disposed.

Hydraulic pumps of this type, preferably employed when high pressuresare involved, demand very fine machining of the component parts,extremely close tolerances and the maintenance of constant lubricationbetween the moving parts. The latter task in particular requirescontinuous removal of the heat associated with high pressures and thecorrelated friction between moving parts. Furthermore, the efficiency ofother pump components is liable to be affected by a thermal distortionof the lubrieating means or by their decomposition into substances whichare ineflectual as lubricants or incompatible with the metallic andnon-metallic parts with which they are in contact.

It is therefore the primary object of this invention to supply theworking elements of a radial piston pump with the moderate environmentaltemperatures necessary to maintain the effective lubrication of themoving parts.

These objects and others which will bec me apparent hereinafter areattained, in accordance with the present invention, by routing theworking hydraulic fluid on its way from the fluid reservoir to thepiston cylinder intake chamber so as to flow past heat-sensitivesurfaces and to carry away the undersirable heat. Specifically, thecircuitous flow pattern leads fresh cool hydraulic fluid in and out ofthe rotor shaft which carries the slidable jacket designed to controlthe length of the piston stroke, and past and through the jacket orsleeve surrounding the eccentric.

According to a more specific feature of this invention, the eccentricshaft is rotatably received in a blind bore of the pump or cylinderhousing which communicates, at its closed end, with the intake port ofthe pump and delivers hydraulic fluid to an annular suction chamberwithin the housing communicating with the pump cylinders. At least partof the fluid delivered from the intake portion to the suction chamber ispassed through an axial bore formed in the eccentric shaft at its endproximal to the closed end of the axial bore of the housing. Spaced fromthis end of the shaft, there is provided an eccentric portion aroundwhich a bearing sleeve or jacket is disposed with peripheral clearance,the axial bore of the shaft opening within the sleeve via one or moreradial ports formed in the eccentric portion of the shaft. The sleeveis, according to another feature of this invention, formed with openingscommunicating between its interior (with which the radial portscommunicate) and the annular space in the axial bore of the housingsurrounding the sleeve and into which the pistons project to contact thesleeve. This annular space is, in turn, connected with the suctionchamber of the housing by one or more channels.

The system described generally above has the advantage that at leastpart of the hydraulic fluid displaced by the pump traverses theeccentric shaft and the bearing surfaces of the sleeve therearoundbefore passage into the suction compartment and thus provides a constantstream of cool fresh lubricant and coolant.

The above and other objects, features and advantages of this inventionwill become more readily apparent from the following description,reference being made to the accompanying drawing in which:

FIG. 1 is an axial cross-sectional view, in part, of this invention in asomewhat schematical representation; and

FIG. 2 is a longitudinal cross-sectional view of the embodiment shown inFIG. 1 taken along the line II--II.

In FIGS. 1 and 2 there is shown a radial piston pump whose eccentricdrive shaft 2 is rotatable in the housing 1 and has an eccentric portion12 carrying the bearing jacket, sleeve or ring 3 on its circumference.The bearing 3 is radially shiftable on the shaft 2 and serves todisplace a plurality of radial pistons 4 to pump the fluid upon rotationof the shaft 2 which is received in a closed-end axial bore 28. Theradially extending cylinders 19 in which the pistons are slidable in thedirection of the arrow 5 communicate with the annular low-pressure orsuction chamber 21 and with the high-pressure discharge chamber 7 fromwhich the hydraulic fluid is lead via outlet port 8. The spring-loadedcheck valves 20 between the heads of the cylinders 19 and the chamber 7permits the fluid to flow only in one direction between the cylinder andthe chamber 7.

The pistons 4, biased by the compression springs 6 in against thebearing sleeve 3, are two of a larger number (not shown) of pistonelements radially disposed in the housing 1 and reciprocated between theintake or suction position indicated at 4a and discharge or com pressionposition indicated at 4b for the displacement of the hydraulic fluid.

According to this invention, the shaft 2 is provided with an axial bore10 open at its end face 11 (proximal to the closed end of bore 28)toward an intake chamber 15 which communicates with the fluid-intakeport 14 leading to the reservoir 14a. The bore 10 extends to a locationin the interior of the shaft 2 which is approximately in line with thepistons 4, 4a, 4b which lie in a common radial plane. Radial bores 13(only one shown) lead from the axial bore 10 to the annular clearance 22surrounding the shaft 2, where they terminate at a milled surface 9which is surrounded by the annular clearance 22 between the sleeve 3 andthis surface. The clearance 22 between the external surface of theeccentric portion 12 of shaft 2 and the inner wall 23 of the bearingsleeve 3, communicates, via radial milled slots 24 in the edges ofbearing sleeve 3, with the annular space 25. Space 25 which receives theends of the pistons 4 co-operating with the sliding jacket 3 as well asthe sliding jacket, is connected by the radial channel 26 with theannular suction chamber 21. During radial inward movement, the leadingedge 4' of each piston 4 is withdrawn sufficiently inwardly of edge 21'of the suction chamber to admit fluid into the respective cylinder aheadof the piston. During the outward movement of the piston, the edge 4'passes edge 21' to close the cylinder with further movement driving thefluid past the check valve into the outlet chamber 7.

The fluid flow, according to this invention, occurs in the direction ofthe arrows and broken lines and proceeds along a first conduit from thereservoir 14a through the port 14 into the chamber 15, past theproximate part of the frontal area 11 of the extremity of shaft 2, intothe axial bore thereof, through the radial orifices 13 to the smoothmilled surface 9 of the clearance 22 within the bearing sleeve 3,through the radial cutouts, notches or slots 24 in the axially oppositeannular ends of the bearing sleeve 3, to the chamber 25 and from therethrough the radial passage 26 to the suction chamber 21. The coolingeffected by the circulation of the fluid in the described manner is inexcess of and supplementary to the heat transfer normally provided bythe controlled leakage of hydraulic fluid in radial-piston pump systems.According to the drawing, the leakage is represented by the dot-dashlines leading from the chamber 25 through the narrow clearance betweenthe shaft 2 and the bore 28 in which it is housed, into the radialchannel 30 proximate to the packing or sealed bearing 27, and fromtherethrough the pas sageway 29 to the chamber 21.

What is claimed is:

1. A radial-piston pump comprising:

a housing formed with an axially extending housing bore;

an eccentric shaft rotatably received in said housing bore and providedwith an eccentric portion therealong;

at least one cylinder formed in said housing and slidably receiving apiston driven by said shaft;

a suction chamber and a fluid-discharge chamber formed in said housingand communicating with said cylinder for displacement of fluid from saidsuction chamber to said discharge chamber upon rotation of said shaftand reciprocation of said piston;

a fluid-intake port formed in said housing;

a sleeve surrounding said eccentric portion of said shaft and actingupon said piston for displacing same upon rotation of said shaft, saidshaft having a pair of bearing portions flanking said sleeve in saidhousing and being provided with an extremity; and

at least one passageway having at least a portion extending through saidextremity of said shaft and communicating with said intake ports whileopening Within said sleeve and between said sleeve and said eccentricportion for cooling the pump and lubricating said sleeve, said portionof said passageway being formed as an axial bore in said shaft andopening at said extremity thereof, said eccentric portion in said shaftbeing formed with at least one radial orifice communicating with theaxial bore of said shaft and opening within said sleeve, said bearingportions defining leakage paths for said fluid between said intake portand said suction chamber so constructed and arranged that all fluidcommunication between said intake port and said suction chamber isconstituted by said leakage paths and said axial bore, said sleevedefining an annular inner clearance with said eccentric portion of saidshaft and an annular outer space with a wall of said housing bothsurrounding said sleeve, said orifice opening into said clearance, saidsleeve being formed with at least one channel connecting said clearancewith said space, said space being separate from said suction chamber,said housing being provided with a bore connecting said space with 4said suction chamber and dimensioned to lead some of the fluidaccumulated in said space into said suction chamber and to direct theremainder of said fluid along one of said leakage paths.

2. The pump defined in claim 1 wherein said channel is one of amultiplicity of notches formed in the opposite axial ends of saidsleeve.

3. The pump defined in claim 1 wherein said piston and said cylinder liein a radial plane of said housing, said orifice lying substantially insaid plane and said axial bore of said shaft extending through thelatter substantially to said radial plane.

4. The pump defined in claim 1 wherein said housing is formed with afluid-intake chamber axially flanking said extremity of said shaft andcommunicating with said fluidintake port, said bore in said shaftcommunicating with said fluid-intake chamber and opening axiallydirectly into the latter, one of said bearing portions being locatedbetween said intake chamber and said space and defining a first one ofsaid leakage paths between said fluid-intake chamber and said space,said pump further comprising seal means surrounding said shaft remotefrom said extremity and defining a fluid-collection compartment aroundsaid shaft spaced from said space, the shaft region between saidcollection compartment and said space constituting the other bearingportion and defining the second of said leakage paths between said spaceand said collecting compartment, said suction chamber being angular andsurrounding said shaft, said bore connecting said space with saidsuction chamber being generally radial, said housing being formed with apassage interconnecting said collection compartment and said suctionchamber and having a cross-section larger than said bore connecting saidspace with said suction chamber, a plurality of such cylinders beingformed in said housing in a common radial plane perpendicular to saidshaft and in angularly equispaced relation about the axis thereof, eachof said cylinders having a respective piston bearing radially upon saidsleeve, said suction chamber communicating with all said cylinders, saidfluid-discharge chamber being annular and coaxial with said suctionchamber and communicating with all of said cylinders, each of saidcylinders being provided with check-valve means permittingunidirectional fluid flow from said suction chamber to saidfluid-discharge chamber upon reciprocation of the respective piston.

References Cited UNITED STATES PATENTS 2,394,285 2/ 1946 Beuins 103-1742,612,837 10/1952 Midgette 103-174 2,693,150 11/1954 Dichard et al103-174 2,865,292 12/1958 Raibaud 103-171 3,125,034 3/1964 Lucien103-174 3,259,074 7/1966 Erdmann 103-174 FOREIGN PATENTS 902,097 8/ 1945France.

WILLIAM L. FREEH, Primary Examiner U.S. Cl. X.R.

